You can try this registry edit and see if it fixes the problem for you. Open Regedit by going to Start, Run and typing in regedit and clicking ok.
Then navigate to
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU
Select this dword value that says
"UseWUServer"=dword:00000001"
and change the value to 0 if you have this entry in your registry.
Reboot the computer and try to do your updates again.
It can also be caused by a spyware infection. Some people have had good results after running Malwarebytes on the computer. You can try other spyware programs as well.
You can also try to reset your DSL/Cable modem and router if you have one. Its possible that you may have some incorrect DNS settings causing the problem.